Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 242 PM EST Sat Dec 17 2016 Valid 00Z Sun Dec 18 2016 - 00Z Tue Dec 20 2016 ...Strong storm system continues to impact the southern and eastern states this weekend... An expansive cold front, extending from the Great Lakes region southwest through the southern Plains/Rockies and into northern Mexico will continue to push eastward over the next couple of days. In addition, a warm front will lift through the Appalachians/Mid-Atlantic and Northeast; which will erode the cold air that has been dammed near the Appalachian Range. Widespread rain will accompany the front spanning from the Lower Mississippi Valley to New England; however a swath of mixed precipitation is expected on the backside before transitioning to all snow once a secondary cold front moves through. This reinforcing cold air and frontal passage will keep snow generating off the Great Lakes - areas in the favored downwind locations may have another round of lake-enhanced snowfall. Arctic air will continue to surge southward along the Front Range and into the Plains under the vast area of high pressure. A tremendous temperature gradient is expected in the vicinity of the front across Oklahoma and Texas, with 60s and 70s south of the front, and sub-freezing temperatures behind it. Readings could fall as much as 25 degrees in one hour with the cold frontal passage! The cold air mass is forecast to remain over much of the West and central U.S. The East will revert to a mild, less active pattern once the front moves offshore. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php